C#: Extract Charset from Html Meta Tag

private static readonly Regex META_TAG_CHARSET_REGEX = new Regex(@"<META\s+http-equiv\s*=\s*Content-Type\s+content=\s*""[^""]*\s+charset\s*=\s*(?<charset>[^""\s]*).*""\s*>", 
RegexOptions.IgnoreCase | RegexOptions.Compiled);

public static string ExtractCharset(string htmlText)
{
    string result = null;
    var m = META_TAG_CHARSET_REGEX.Match(htmlText);
    if (m.Success)
    {
        result = m.Groups["charset"].Value;
    }
    return result;
}

Note: System.Text.RegularExpressions.Regex class is thread safe according to this msdn doc.